Some aspects of the recent discussion in the previous post, got me thinking about West Eurasian founder effects, or major haplogroups and the possibility that they may reflect a number of coalescence areas or populations.
So I got to consider the founder lineages of West Eurasians, let's see:
- Major: R0 (incl. HV), U (incl. K), JT
- Minor: N1 (incl. I), X, W, M1
- Uralic-related: CZ, D (probably later arrivals via Siberia)
- African flows: L(xM,N) (not going to detail them here)
- Major: R1b, IJ, G and maybe R1a (or a subclade of it)
- Minor: T, L, Q
- Uralic-related: N
- African flows: E1b1b1
Something that is quite apparent is that the number of lineages in each category (specially if we ignore the Uralic and African groups, which clearly belong to different processes) are not too different between Y-DNA and mtDNA, what suggests that each pair represents a founder population, specially among the major haplogroups. Another thing is how to pair them and even if doing that makes any sense at all but it's quite possible that at the beginnings of the colonization of West Eurasia they were coupled to a great extent because of the well known phenomenon of fixation by drift in small populations.
So I am guessing that there were like up to six or seven founder populations (maybe less as fixation does not need to be absolute, specially not in expansive contexts) some 50 millennia ago in West Asia. If we only consider the major clades, maybe these were just three.
Where did they exist? That I'll leave up to you. The details of the MP-UP transition in West Eurasia are not fully well understood and there seems to be blanks in the research. Some specific regions can be Palestine (clearly so), Central Asia, the Zagros mountains... an oasis area in the Persian Gulf (now submerged) has been proposed recently too... parts of Anatolia surely played a role, though here is where one of the most critical blanks exist...
Anyhow, most if not all these lineages are wildly scattered, so, while their West Asian origin is certain, the exact locations in this area are not at all clear. Maybe I am wrong and they were all part of a single founder population with only some, now blurred, structure.
As I say, just a working note. Thinking loud so you feel free to provide feedback and opinions. Cheers.